super.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

/*
 *  linux/fs/ext2/super.c
 *
 *  Copyright (C) 1992, 1993, 1994  Remy Card ([e-mail])
 *                                  Laboratoire MASI - Institut Blaise Pascal
 *                                  Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <stdarg.h>

#include <asm/segment.h>
#include <asm/system.h>

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/locks.h>

extern int vsprintf (char *, const char *, va_list);

void ext2_error (struct super_block * sb, const char * function,
		 const char * fmt, ...)
{
	char buf[1024];
	va_list args;

	if (!(sb->s_flags & MS_RDONLY)) {
		sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
		sb->u.ext2_sb.s_es->s_state |= EXT2_ERROR_FS;
		sb->u.ext2_sb.s_sbh->b_dirt = 1;
		sb->s_dirt = 1;
	}
	va_start (args, fmt);
	vsprintf (buf, fmt, args);
	va_end (args);
	if (test_opt (sb, ERRORS_PANIC) ||
	    (sb->u.ext2_sb.s_es->s_errors == EXT2_ERRORS_PANIC &&
	     !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_RO)))
		panic ("EXT2-fs panic (device %d/%d): %s: %s\n",
		       MAJOR(sb->s_dev), MINOR(sb->s_dev), function, buf);
	printk (KERN_CRIT "EXT2-fs error (device %d/%d): %s: %s\n",
		MAJOR(sb->s_dev), MINOR(sb->s_dev), function, buf);
	if (test_opt (sb, ERRORS_RO) ||
	    (sb->u.ext2_sb.s_es->s_errors == EXT2_ERRORS_RO &&
	     !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_PANIC))) {
		printk ("Remounting filesystem read-only\n");
		sb->s_flags |= MS_RDONLY;
	}
}

NORET_TYPE void ext2_panic (struct super_block * sb, const char * function,
			    const char * fmt, ...)
{
	char buf[1024];
	va_list args;

	if (!(sb->s_flags & MS_RDONLY)) {
		sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
		sb->u.ext2_sb.s_es->s_state |= EXT2_ERROR_FS;
		sb->u.ext2_sb.s_sbh->b_dirt = 1;
		sb->s_dirt = 1;
	}
	va_start (args, fmt);
	vsprintf (buf, fmt, args);
	va_end (args);
	panic ("EXT2-fs panic (device %d/%d): %s: %s\n",
	       MAJOR(sb->s_dev), MINOR(sb->s_dev), function, buf);
}

void ext2_warning (struct super_block * sb, const char * function,
		   const char * fmt, ...)
{
	char buf[1024];
	va_list args;

	va_start (args, fmt);
	vsprintf (buf, fmt, args);
	va_end (args);
	printk (KERN_WARNING "EXT2-fs warning (device %d/%d): %s: %s\n",
		MAJOR(sb->s_dev), MINOR(sb->s_dev), function, buf);
}

void ext2_put_super (struct super_block * sb)
{
	int i;

	lock_super (sb);
	if (!(sb->s_flags & MS_RDONLY)) {
		sb->u.ext2_sb.s_es->s_state = sb->u.ext2_sb.s_mount_state;
		sb->u.ext2_sb.s_sbh->b_dirt = 1;
	}
#ifndef DONT_USE_DCACHE
	ext2_dcache_invalidate (sb->s_dev);
#endif
	sb->s_dev = 0;
	for (i = 0; i < EXT2_MAX_GROUP_DESC; i++)
		if (sb->u.ext2_sb.s_group_desc[i])
			brelse (sb->u.ext2_sb.s_group_desc[i]);
	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
		if (sb->u.ext2_sb.s_inode_bitmap[i])
			brelse (sb->u.ext2_sb.s_inode_bitmap[i]);
	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
		if (sb->u.ext2_sb.s_block_bitmap[i])
			brelse (sb->u.ext2_sb.s_block_bitmap[i]);
	brelse (sb->u.ext2_sb.s_sbh);
	unlock_super (sb);
	return;
}

static struct super_operations ext2_sops = { 
	ext2_read_inode,
	NULL,
	ext2_write_inode,
	ext2_put_inode,
	ext2_put_super,
	ext2_write_super,
	ext2_statfs,
	ext2_remount
};

#ifdef EXT2FS_PRE_02B_COMPAT

static int convert_pre_02b_fs (struct super_block * sb,
			       struct buffer_head * bh)
{
	struct ext2_super_block * es;
	struct ext2_old_group_desc old_group_desc [BLOCK_SIZE / sizeof (struct ext2_old_group_desc)];
	struct ext2_group_desc * gdp;
	struct buffer_head * bh2;
	int groups_count;
	int i;

	es = (struct ext2_super_block *) bh->b_data;
	bh2 = bread (sb->s_dev, 2, BLOCK_SIZE);
	if (!bh2) {
		printk ("Cannot read descriptor blocks while converting !\n");
		return 0;
	}
	memcpy (old_group_desc, bh2->b_data, BLOCK_SIZE);
	groups_count = (sb->u.ext2_sb.s_blocks_count - 
			sb->u.ext2_sb.s_first_data_block +
			(EXT2_BLOCK_SIZE(sb) * 8) - 1) /
				(EXT2_BLOCK_SIZE(sb) * 8);
	memset (bh2->b_data, 0, BLOCK_SIZE);
	gdp = (struct ext2_group_desc *) bh2->b_data;
	for (i = 0; i < groups_count; i++) {
		gdp[i].bg_block_bitmap = old_group_desc[i].bg_block_bitmap;
		gdp[i].bg_inode_bitmap = old_group_desc[i].bg_inode_bitmap;
		gdp[i].bg_inode_table = old_group_desc[i].bg_inode_table;
		gdp[i].bg_free_blocks_count = old_group_desc[i].bg_free_blocks_count;
		gdp[i].bg_free_inodes_count = old_group_desc[i].bg_free_inodes_count;
	}
	bh2->b_dirt = 1;
	brelse (bh2);
	es->s_magic = EXT2_SUPER_MAGIC;
	bh->b_dirt = 1;
	sb->s_magic = EXT2_SUPER_MAGIC;
	return 1;
}

#endif

/*
 * This function has been shamelessly adapted from the msdos fs
 */
static int parse_options (char * options, unsigned long * sb_block,
			  unsigned long * mount_options)
{
	char * this_char;
	char * value;

	if (!options)
		return 1;
	for (this_char = strtok (options, ",");
	     this_char != NULL;
	     this_char = strtok (NULL, ",")) {
		if ((value = strchr (this_char, '=')) != NULL)
			*value++ = 0;
		if (!strcmp (this_char, "check")) {
			if (!value || !*value)
				set_opt (*mount_options, CHECK_NORMAL);
			else if (!strcmp (value, "none")) {
				clear_opt (*mount_options, CHECK_NORMAL);
				clear_opt (*mount_options, CHECK_STRICT);
			}
			else if (strcmp (value, "normal"))
				set_opt (*mount_options, CHECK_NORMAL);
			else if (strcmp (value, "strict")) {
				set_opt (*mount_options, CHECK_NORMAL);
				set_opt (*mount_options, CHECK_STRICT);
			}
			else {
				printk ("EXT2-fs: Invalid check option: %s\n",
					value);
				return 0;
			}
		}
		else if (!strcmp (this_char, "debug"))
			set_opt (*mount_options, DEBUG);
		else if (!strcmp (this_char, "errors")) {
			if (!value || !*value) {
				printk ("EXT2-fs: the errors option requires "
					"an argument");
				return 0;
			}
			if (!strcmp (value, "continue")) {
				clear_opt (*mount_options, ERRORS_RO);
				clear_opt (*mount_options, ERRORS_PANIC);
				set_opt (*mount_options, ERRORS_CONT);
			}
			else if (!strcmp (value, "remount-ro")) {
				clear_opt (*mount_options, ERRORS_CONT);
				clear_opt (*mount_options, ERRORS_PANIC);
				set_opt (*mount_options, ERRORS_RO);
			}
			else if (!strcmp (value, "panic")) {
				clear_opt (*mount_options, ERRORS_CONT);
				clear_opt (*mount_options, ERRORS_RO);
				set_opt (*mount_options, ERRORS_PANIC);
			}
			else {
				printk ("EXT2-fs: Invalid errors option: %s\n",
					value);
				return 0;
			}
		}
		else if (!strcmp (this_char, "grpid") ||
			 !strcmp (this_char, "bsdgroups"))
			set_opt (*mount_options, GRPID);
		else if (!strcmp (this_char, "nocheck")) {
			clear_opt (*mount_options, CHECK_NORMAL);
			clear_opt (*mount_options, CHECK_STRICT);
		}
		else if (!strcmp (this_char, "nogrpid") ||
			 !strcmp (this_char, "sysvgroups"))
			clear_opt (*mount_options, GRPID);
		else if (!strcmp (this_char, "sb")) {
			if (!value || !*value) {
				printk ("EXT2-fs: the sb option requires "
					"an argument");
				return 0;
			}
			*sb_block = simple_strtoul (value, &value, 0);
			if (*value) {
				printk ("EXT2-fs: Invalid sb option: %s\n",
					value);
				return 0;
			}
		}
		else {
			printk ("EXT2-fs: Unrecognized mount option %s\n", this_char);
			return 0;
		}
	}
	return 1;
}

static void ext2_setup_super (struct super_block * sb,
			      struct ext2_super_block * es)
{
	if (!(sb->s_flags & MS_RDONLY)) {
		if (!(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
			printk ("EXT2-fs warning: mounting unchecked fs, "
				"running e2fsck is recommended\n");
		else if ((sb->u.ext2_sb.s_mount_state & EXT2_ERROR_FS))
			printk ("EXT2-fs warning: mounting fs with errors, "
				"running e2fsck is recommended\n");
		else if (es->s_max_mnt_count >= 0 &&
		         es->s_mnt_count >= (unsigned short) es->s_max_mnt_count)
			printk ("EXT2-fs warning: maximal mount count reached, "
				"running e2fsck is recommended\n");
		else if (es->s_checkinterval &&
			(es->s_lastcheck + es->s_checkinterval <= CURRENT_TIME))
			printk ("EXT2-fs warning: checktime reached, "
				"running e2fsck is recommended\n");
		es->s_state &= ~EXT2_VALID_FS;
		if (!es->s_max_mnt_count)
			es->s_max_mnt_count = EXT2_DFL_MAX_MNT_COUNT;
		es->s_mnt_count++;
		es->s_mtime = CURRENT_TIME;
		sb->u.ext2_sb.s_sbh->b_dirt = 1;
		sb->s_dirt = 1;
		if (test_opt (sb, DEBUG))
			printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
				"bpg=%lu, ipg=%lu, mo=%04lx]\n",
				EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
				sb->u.ext2_sb.s_frag_size,
				sb->u.ext2_sb.s_groups_count,
				EXT2_BLOCKS_PER_GROUP(sb),
				EXT2_INODES_PER_GROUP(sb),
				sb->u.ext2_sb.s_mount_opt);
		if (test_opt (sb, CHECK)) {
			ext2_check_blocks_bitmap (sb);
			ext2_check_inodes_bitmap (sb);
		}
	}
}

static int ext2_check_descriptors (struct super_block * sb)
{
	int i;
	int desc_block = 0;
	unsigned long block = sb->u.ext2_sb.s_es->s_first_data_block;
	struct ext2_group_desc * gdp = NULL;

	ext2_debug ("Checking group descriptors");

	for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++)
	{
		if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
			gdp = (struct ext2_group_desc *) sb->u.ext2_sb.s_group_desc[desc_block++]->b_data;
		if (gdp->bg_block_bitmap < block ||
		    gdp->bg_block_bitmap >= block + EXT2_BLOCKS_PER_GROUP(sb))
		{
			ext2_error (sb, "ext2_check_desciptors",
				    "Block bitmap for group %d"
				    " not in group (block %lu)!",
				    i, gdp->bg_block_bitmap);
			return 0;
		}
		if (gdp->bg_inode_bitmap < block ||
		    gdp->bg_inode_bitmap >= block + EXT2_BLOCKS_PER_GROUP(sb))
		{
			ext2_error (sb, "ext2_check_desciptors",
				    "Inode bitmap for group %d"
				    " not in group (block %lu)!",
				    i, gdp->bg_inode_bitmap);
			return 0;
		}
		if (gdp->bg_inode_table < block ||